The magnetocaloric effect (MCE) refers to an effect in which a magnetic field causes either warming or cooling in a magnetic sample when the magnetic field is applied in the vicinity of the material's Curie temperature. A change in temperature results from a change in the magnetic entropy of the system (e.g., alignment of spins) when the field is applied. Due to this effect, it may be possible to develop a magnetization versus temperature cycle that results in magnetic cooling (e.g., a magnetic refrigerator) or heating (e.g., a magnetic heater). The magnetic cooling cycle may be referred to as a magnetic Stirling cycle. For example, Ames Laboratory and Astronautics Corp. of America have built a demonstration magnetic refrigerator using Gd spheres (˜150-300 microns in diameter) with a 5-Tesla magnet and yielded 600 W cooling power producing a ΔT=38K with up to 60% Carnot efficiency. The unit operated with a cycle of 0.17 Hz.